A "freeze" effect is defmed for purposes of this application as a photographic effect where a moving subject is still-photographed from multiple perspectives simultaneously. The resulting images are then placed in a sequential order, based on angular or linear displacement, to form a moving picture, like a movie. Thus, the end product is a moving picture of an active subject frozen in time. A "freeze" creates the illusion of freezing in time an active subject while a movie camera photographs the subject from multiple perspectives.
To successfully create a "freeze," shutter timing is critical. The images must be made as close to simultaneously as possible. Because shutter speeds are measured in units as small as hundredths of a second, the slightest a synchronicity will destroy the effect: i.e., all the images will not be "frozen" at the same time, resulting in a moving picture where the subject appears to "jump" about.
To solve this problem, one existing method utilizes a single camera and a single piece of film. This camera has a single shutter controlling exposure through several lenses. The single shutter simultaneously exposes the film at different places through the different lenses, eliminating the need to synchronize multiple shutters. This single-shutter method, however, limits the camera's--and the viewers'--perspectives by limiting the possible linear displacement between the lenses and the displacement between the first and last lens. Further, a single shutter limits the lenses' arrangement to a line, or, using a camera constructed of a flexible material, a shallow arc. Finally, the single shutter limits the number of lenses through which the film may be exposed. This limits the number of images that the camera can create and, consequently, the length--in time--of the moving picture.
To create a longer "freeze" and a wider total linear and angular displacement, multiple shutters/cameras are necessary. However, using multiple shutters raises the problem of shutter asynchronicity and the resulting subject "jumpiness" in the moving picture product. A computer-enhancement technique known as "interlacing" minimizes this problem.
"Interlacing" works as follows: Suppose three cameras, A, B, and C, are arranged from left to right and fired simultaneously (or as close to simultaneously as possible) to create a "freeze." The computer "interlaces" the right half of camera A's image with the left half of camera B's image to form a new, "interlaced" image AB. Likewise, the right half of camera B's image is "interlaced" with the left half of camera C's image to form BC. In the resulting image sequence--A-AB-B-BC-C--shutter timing differences are minimized, or smoothed out. However, the resulting moving picture's quality is less than it would be if the shutters could be perfectly, or almost perfectly, synchronized.
This shutter synchronization must be virtually complete. Even if the shutters operate within hundredths of a second of one another, the resulting "freeze" will be ruined. For example, assume that the subject, or part of the subject, moves at fifty (50) feet per second. If the shutters each operate within one one-hundredth (1/100) of a second of one another, the images captured will still vary in space by as much as six (6) inches.
The photographer must solve a number of problems to synchronize more than one camera shutter. One problem to solve when synchronizing multiple cameras' shutters is firing all the cameras simultaneously. However, even if each camera begins the shutter operation process simultaneously, each shutter may not operate simultaneously. This is because of inherent timing tolerance differences within each camera's controlling circuitry, or central processing unit (CPU). Finally, an internal or external DC power supply typically powers a camera. Small variations in DC power supply voltage between two cameras can vary the speed with which the cameras' CPUs send a "fire" signal to their respective shutters. This power supply-dependent asynchronization can also destroy a "freeze." Therefore, a need exists for a method of creating a "freeze" effect using multiple cameras/lenses/shutters by synchronizing the shutters and eliminating shutter asynchronicity instead of "interlacing" the images.